Flexible carbon capture using MOF fixed bed adsorbers at an NGCC plant

Abstract

Novel carbon capture systems are necessary to help natural gas power plants approach net zero CO2 emissions. We propose a hybrid carbon capture system attached to a natural gas combined cycle (NGCC) power plant that consists of a membrane system and a solid sorbent system, with this work focusing on the design of the solid sorbent system. We modeled fixed bed adsorbers that are packed with metal-organic framework (MOF) solid sorbents that adsorb CO2 and undergo temperature swing desorption using steam from the power plant. Parametric simulation of adsorber conditions showed that ten 5-m diameter beds adsorbing in parallel with 4.9 bars inlet gas pressure and 1.5 bars of steam pressure at a flow rate of 0.15 kmol/s led to optimized performance. This study enabled us to determine that the MOF bed adsorber can attain 86.6 % and 85.4 % carbon capture during peak and off-peak operation, respectively. When combined with the membrane capture system, this results in overall capture rates of 98.4 % and 98.9 % during peak and off-peak operation, respectively. Although we were unable to attain net-zero or net-negative emissions in this study, we are confident that net-negative operation could be obtained in future work by selecting a solid sorbent better suited to direct air capture conditions so that more air could be processed by the solid sorbent system.